An improved ratiometric fluorescent tag based on aggregation-induced emission luminogen for in-situ monitoring of seafood freshness

Abstract

Volatile basic nitrogens (VBNs) are an important indicator of food freshness. In this work, a novel ratiometric fluorescent sensor was developed. The sensor used blue-green fluorescent N-acetyl-L-cysteine capped silver nanoclusters (NAC-AgNCs) as an indicator and red-orange fluorescent glutathione capped gold nanoclusters (GSH-AuNCs) as an internal reference. With biogenic amines as model targets, results showed that the sensor was sensitive to VBNs with a limit of detection of 3.85 μM and 6.75 μM for spermidine and spermine, respectively. Based on these findings, a ratiometric fluorescent tag was further prepared and applied as a gas sensor for ammonia vapour monitoring, which was employed and validated to monitor the freshness of raw shrimp at different storage temperatures (4 and 25 °C). For all we know, this is the first ratiometric fluorescent tag based on metal nanoclusters with aggregation-induced emission properties for monitoring seafood freshness.